Body implantable stimulators are known to the prior art, the most common being the cardiac pacemaker. Typically, such stimulators are formed of a separable lead and signal generator assembly with provision being made to electrically and mechanically interconnect the lead and generator to complete the stimulator unit.
Many prior art signal generators have been formed by molding the components, including mechanical and electrical connections for the lead, in a matrix of encapsulating material which supports the components and shields them from the body environment. Typically, the encapsulating material is an epoxy.
In the body environment it is generally recognized that an enclosed and hermetically sealed signal generator is more reliable as a result of the known and controlled environment provided by the hermetic seal. For this reason, many recent signal generator designs include a rigid enclosure formed of a plurality of preformed members which may be welded together to complete the enclosure. The interconnection between the generator and the lead, when it is desired that these members be separable, occurs outside of the enclosure. While it is common to mold an interconnect assembly from epoxy, such a process diminishes a benefit of a preformed enclosure--elimination of the epoxy encapsulation process. Thus a preformed interconnect assembly, which may be reliably secured to a preformed enclosure housing the generator components, would greatly facilitate assembly of the stimulator. The amount of handling would be reduced with the remaining handling being easier to perform than an epoxy molding process.
A preformed interconnect assembly is disclosed in application Ser. No. 793,642, filed May 4, 1977 in the name of Richard A. Jones, which application is commonly owned with the present invention. The interconnect assembly of the referenced application eliminates the necessity of forming that assembly in place, as by an epoxy molding process, for example. However, that preformed assembly still requires the use of epoxy, or a similar substance, to adhere it to the signal generator enclosure. Additionally, the electrical connection between the interconnect assembly terminal and the signal generator requires manipulation of a wire to position it and a weld, or other process, to secure it in position. Thus, while the interconnect assembly of the referenced application greatly reduces the handling necessary to form and position an interconnect assembly on a signal generator unit, considerable handling remains necessary.
An improvement over the above referenced interconnect assembly is disclosed in application Ser. No. 894,358, filed Apr. 7, 1978, in the name of Lyle A. Ware, which application is commonly owned with the present invention. The invention of the second referenced application provides a preformed interconnect assembly or connector which may be mechanically secured to a signal generator thereby eliminating the need to use epoxy, or a similar substance, to secure the connector to the generator. A hook and a threaded stud extend from a platform on the signal generator. The hook engages an aperture in the preformed connector while the threaded stud extends through a second aperture wherein it is engaged by a nut. Electrical communication with the signal generator components is via upstanding feed-through connections which engage terminals carried within the connector. The signal generator assembly is assembled by first engaging the hook within its aperture, aligning the feed-through connections with apertures which extend to the connector terminals, and pivoting the connector about the hook to insert the stud and feed-through connections within their associated apertures. On tighting of the nut, the connector is firmly secured to the signal generator unit. However, the pivotable motion necessary on assembly provides a cumbersome alignment between the feed-through connections and their associated apertures. Additionally, the threaded stud and nut arrangement may be easily tampered with, without detection.